To determine the pathways of benzo(a)pyrene (BP) oxidation in hamster embryo cell cultures, it is necessary to be able to analyze the many water-soluble benzo(a)pyrene metabolites that are formed. We have shown that a major portion (more than 3%) of the total BP metabolites formed in these cells were glucuronic acid conjugates of two Bp-phenols, 9-hydroxy-BP and 3-hydroxy-BP. In contrast to the organic solvent-soluble metabolites that were mainly BP-dihydrodiols, the glucuronide conjugates were almost entirely BP-phenols and BP-quinones. Thus, the metabolite profile obtained by Beta-glucuronidase treatments allows a considerably more accurate determination of the pathways of BP oxidation in these cells. Preliminary studies of the effects of various tumor promoters and cocarcinogens on BP metabolism in these cells suggest that tumor promoters do not significantly alter BP metabolism, but that cocarcinogens do. BIBLIOGRAPHIC REFERENCE: Baird, W.M., Chern, C.J. and Diamond L. Formation of Benzo(a)pyrene-Glucuronides in Cell Culture. Proc. Am. Assoc. Cancer Res. 18, 1977, in press.